Message documentation filled with senseless content

I think he means the editing area. I have the same issue for Lower Sorbian (but not for Upper Sorbian). This issue occurs in normal editing mode only, in ajax editing area it doesn't occur. The name of the message is inserted within angle brackets which are displayed as HTML entities, e.g:

<revreview-pending-basic> for message revreview-pending-basic

It seems that this appears instead of the text of the fallback language.